Field of the Invention
Embodiments disclosed herein generally relate to a temperature sensor disposed in an apparatus.
Description of the Related Art
Semiconductor device geometries have dramatically decreased in size since such devices were first introduced several decades ago. Since then, integrated circuits have generally followed the two year/half-size rule (often called Moore's Law), which means that the number of devices that will fit on a chip doubles every two years. Today's fabrication plants are routinely producing devices having 45 nanometer feature sizes, and tomorrow's plants will soon be producing devices having even smaller geometries.
Thermal and plasma annealing processes are sometimes used to manufacture semiconductor devices. Thermal and plasma annealing processes may be performed at temperatures of less than about 400 degrees Celsius in order to prevent damage to other components of the substrate or device on which the low dielectric constant film is deposited. As a result, the ability to monitor the temperature at the substrate surface is beneficial to the annealing process. Further, industry production requirements dictate several criteria that should be met when selecting a temperature sensing device or thermocouple.
First, the junction of the thermocouple device should make direct, reliable thermal contact with the surface to be monitored. Otherwise, there is a thermal impedance between the thermocouple junction and the surface resulting in temperature readings more closely related to the material surrounding the thermocouple than to the actual surface temperature.
Second, the mass of material surrounding the thermocouple junction and holding it to the surface should be minimal. The effect of this material is to add thermal mass to the junction and insulation surface beneath the material, both of which cause the thermocouple to lag the true surface temperature.
Finally, the thermocouple surface should not introduce contaminants onto the surface being measured. While a number of thermocouple devices are currently known, they all use a ceramic tip to maximize temperature response. Unfortunately, using the ceramic tip against a surface, such as a silicon wafer surface, in an RF based process results in RF/EMI noise interference.
For the foregoing reasons, there is a need for a temperature measurement device with a good response time, reliable thermal contact, and comprising a material that won't contaminate the object whose temperature is measured.